Fluid injection systems, which are used to inject a medical fluid into a patient, often include one or more reservoirs, to hold the medical fluid, and one or more pressurizing units, to inject the medical fluid. For example, a contrast media powered injection system may include a reservoir of contrast media coupled to a pressurizing unit, from which contrast is injected, to facilitate imaging during certain medical procedures, such as an angiographic or computed tomography (CT) procedure.
The pressurizing units of medical fluid injection systems typically include at least one syringe and a plunger mounted therein. The plunger is moved, for example, by a motorized plunger shaft of the unit, in a first direction, to draw fluid into the syringe, from the one or more reservoirs, and then, in a second direction, to expel the fluid from the syringe and into the patient, for example, via a catheter, which is coupled to the pressurizing unit. Pressurizing units of many medical fluid injections systems typically employ syringe and plunger subassemblies that are disposable. These disposable syringe and plunger subassemblies may be packaged as a set, wherein the plunger is mounted in the syringe. Once assembled into the pressurizing unit, the syringe and plunger may have an operational life spanning multiple injections, for example, preferably up to 10 or more injections. For those pressurizing units that include a permanent plunger shaft, or ram, assembling the syringe and plunger therein includes coupling the shaft to the plunger prior to an injection; and, removing the syringe and plunger from the pressurizing unit, after one or more injections (for example, for replacement with a new syringe and plunger set), includes decoupling of the shaft from the plunger so that the syringe and plunger may be separated from the shaft.